<!DOCTYPE html>
<html>
<head>
    <title>GH-850 index</title>
</head>
<body>
<button id="simple-btn">
    Simple button
</button>
<iframe id="iframe" src="iframe.html" height="200px" width="200px"
        style="left:20px; top:100px; position:absolute"></iframe>
<script>
    window.btnClickCount = 0;

    var simpleBtn = document.getElementById('simple-btn');

    simpleBtn.addEventListener('click', function () {
        window.btnClickCount++;
    });
</script>
</body>
</html>